The present invention relates to a method of measuring a non-linearity of a pattern edge of a pattern formed on a surface of a base plate e.g. a glass plate, a film, or a metal plate etc. and an apparatus for measuring the same.
There have been employed in the art various methods of forming a pattern on a surface of a base plate e.g. a glass plate, a film, or a metal plate etc. For instance, one method is to uniformly coat a photosensitive material on the base plate and to apply a selective exposure to the photosensitive material, thus forming a pattern by photolithographic techniques. Another method is to form a uniform metallic thin film and to irradiate it with a laser beam of a high energy or the like to evaporate the metallic thin film, thus forming a pattern.
However, with these methods, an ideal pattern cannot be formed, giving rise to various undesirable errors. For instance, errors include there are pattern distortion, pattern shift, an error in a line width of the pattern, rounded corner of the pattern, non-linearity in the pattern edge, and lack of clarity in the pattern etc. The non-linearity of the pattern edge among these errors represents the degree of unevenness of edges of a pattern formed. Namely, where a pattern as shown in FIG. 2a is actually formed, pattern edges become uneven as indicated in FIG. 2b. The degree of the non-linearity of the pattern edge is defined by a distance L between the concave and the convex parts of the pattern edge.
Hitherto, a method was employed to magnify the pattern by using an optical microscope or an electron microscope to visually observe the magnified pattern, thus measuring the non-linearity of the pattern edge. However, with this method, it was difficult to quantitatively measure the non-linearity of the pattern edge with high precision. Further, there is a possibility that variations in measured results occur depending upon observers. Another method was to take an enlarged photograph to measure pattern edges by using a scale. However, the drawbacks with the, latter method are that it takes much too time for obtaining the measured result and measurements cannot be made with high precision.